The present invention relates to a new and improved construction of turbine containing a rotor possessing a hub and rotor blades possessing an aerofoil profile or aerofoil cross-section, a working or fluid medium flowing alternately in the one or in the other throughflow direction through the rotor, and the rotor rotating in the same directional sense during both throughflow directions of the working medium.
Under the expression "throughflow direction", as used in this disclosure, there is to be understood the direction of the meridional flow flowing through the rotor, i.e. the component of the flow of the working medium which lies in a plane, the meridional plane, which is taken through the axis of rotation of the rotor and a radian vector.
Such type of turbines are particularly suitable for extracting energy from the movement of the waves of the ocean, however other uses are possible.
In U.S. Pat. No. 4,221,538, granted Sept. 9, 1980 such type of turbine has been disclosed which operates with air as the working medium. This air turbine is mounted at the upper throat of a vessel which is open at its lower region and immerses in water. The water at the lower portion of the vessel ascends and descends under the influence of the waves. As a result, air flows out of the vessel through the vessel throat or flows into the vessel, as the case may be, i.e. the air is moved through the turbine alternately in opposite directions.
The rotor blades of the heretofore known air turbine are arranged in a plane disposed perpendicular to the axis of rotation of the rotor. The aerofoil-shaped profile of the rotor blades consists of a single part or portion which is arranged symmetrically to such plane. The forward end of the profile, viewed in the direction of rotation, is rounded with a larger radius than the rear end of the profile, again viewed with respect to the direction of rotation. If air flows through the throat of the vessel then there is formed at the better rounded forward end of the profile a smaller pressure than at the more intensely or markedly rounded rear end of the profile, which causes a pronounced break-away or detachment of the flow at that location, so that the rotor begins to rotate. Due to the rotation of the rotor there is formed a relative incident flow which is directed at an inclination towards the front end of the profile, constituting the resultant of the vectorial addition of the flow located in the plane of the rotor formed because of the circumferential velocity and the absolute inflow which is directed, if desired, through a guide apparatus or distributor. Because of the relative incident inflow located at an inclination with respect to the profile the rotor rotates and delivers an output or power. In the other opposite throughflow direction of the air the rotor operates in a corresponding manner, and it rotates in the same directional sense. Because of the mentioned symmetry of the rotor the output is low. While it is possible to attain an improvement in this design with an arrangement of symmetrical rotor blades in a number of parallel planes, as taught for instance in the British patent application No. 2,028,929, published Mar. 12, 1980, and the cognate U.S. Pat. No. 4,313,711, granted Feb. 2, 1982, there cannot however be obtained the maximum output and also no optimum efficiency.
Other constructions of turbines or wind motors known to the art have been respectively disclosed in U.S. Pat. No. 1,835,018, granted Dec. 8, 1931, and the published International PCT application PCT/AT79/00007, published Apr. 17, 1980, under International Publication Number WO 80/00733.